Journal of the Ceramic Association, Japan
Online ISSN : 1884-2127
Print ISSN : 0009-0255
ISSN-L : 0009-0255
Volume 71, Issue 810
Displaying 1-14 of 14 articles from this issue
  • Yukio ENDO, Yasushi HASEGAWA, Syoitiro KAWAKUBO
    1963 Volume 71 Issue 810 Pages 103-109
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Abrasive belt grinding hardness, marring hardness and diamond pyramid indentation hardness (Micro-vickers hardness and Knoop hardness) of glasses for practical use have been measured (Table 1 and 2). Among these values good correlations are found between abrasive belt grinding hardness and marring hardness and between Micro-vickers hardness and Knoop hardness. Both micro-indentation hardnesses do not show notable relation with the other two (Fig. 7/10 and Table 4). None of these values have distinct bearing on transformation point of glasses tested.
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  • Eiji ANBO
    1963 Volume 71 Issue 810 Pages 109-119
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    It is well known that sesquioxides, Cr2O3, Al2O3 and Fe2O3, are liberated from chromite ore by heat treatment in air. But behaviors of the sesquioxides in ores fired at temperatures below 1000°C have not been studied systematically.
    In this report, influences of behaviors of the sesquioxides on lattice spacing of the chromite fired below 1300°C and diffusion phenomena of the sesquioxides in the fired chromite grain were examined by X-ray diffraction and fluorescent X-ray analysis. The followings were observed (1) The lattice spacing (440) of the chromite decreased with elevation of heating temperature up to 700°-900°C in air and increased over these temperatures. The diffracted line (440) was most broadened at 700°-900°C. The X-ray pattern of the sesquioxides in α-type appeared over 700°C, and the relative intensity of the diffracted line (014) increased with decrease of its lattice spacing (014) between 700° and 1300°C. (2) By fluorescent X-ray analysis of the chromite grain, ratio of Fe2O3/Cr2O3 on the surface of the grain fired was determined. The ratio increased in the temperature range between 700° and 1100°C, and over this range decreased. So diffusion of the liberated sesguioxides in the spinel phase which presumably consists of a single crystal, was ascertamed.
    It was concluded that by the liberation of the sesquioxides the chromite phase was made unstable at the heating temperature of 700°-900°C, but was brought into a stable state over 700°-900°C by isolation of two different crystal phases of the sesquioxides and the spinel, with formation of a solid solution of the sesquioxides. The degree of crystallization of the two different phases was raised by heating over 700°-900°C.
    The author considers that the behaviors, as described above, of the sesquioxide deposited on the surface of the chromite crysta will give a valuable explanation of reactions with the chromite grain.
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  • Hiroshi OKUDA, Shuzo KATO, Takeo IGA
    1963 Volume 71 Issue 810 Pages 119-128
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    A large number of kaolinitic-clays of various structures and impurities were examined by differential thermal analysis and X-ray diffraction method. Effects of crystalliniety of kaolinite minerals and of impurities contained within the clays on the exothermic reactions above 1, 000°C were investigated.
    The results obtained were as follows:
    1) The second exothermic reacion at about 1, 200°-1, 250°C results from formation of mullite and shape of the thermal peak depends on the crystallinity of initial kaolinitic clays. In well-crystallized clays, mullite crystal develops at lower temperature than that of poorly crystallized ones and continues to develop with increasing temperature. On the contrary, rapid development of mullite is observed in poorly crystallized ones at about 1, 200°-1250°C. The second exothermic reaction for well-crystallized ones, therefore, show more broad peak than that of poorly crystallized ones.
    2) Further, the third exothermic reaction occures in some clays in the temperature range of 1, 300°-1, 450°C at which cristobalite is more clearly defined. These thermal peak are greatly affected by alkali contained within the clays. The third exothermic peak of clays. containing a small amounts of alkali occures at 1, 400°-1, 450°C. When the amount of alkali in clays increases, the temperature of the thermal peak lowers and the intensity of the peak decreases. Consequently, the third exothermic reaction is not observed for some clays which contain alkali more than a limited amount.
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  • Hajime SAITO, Nobuo TAKUSAGAWA
    1963 Volume 71 Issue 810 Pages 129-133
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Regarding devitrification of the glass which has chemical composition of K2O⋅4PbO⋅8SiO2, effects of particle size and heating processes on properties of resulting polycrystalline material were investigated. Rate of nucleation, rate of nuclei growth, ratio of crystalline phase to vitreous phase and bending strength of products are measured under various conditions of particle size, heating temperature, heating time and other heating treatments.
    The results obtained are as follows.
    (1) The glass softens in the temperature range of 450°C to 500°C and is devitrificated in the temperature range of 580°C to 780°C.
    (2) For nucleation, the temperature of 680°C is the most favorable and smaller particle size of the original glass is the more favorable since the nucleation tends to occur near the surface of the glass.
    (3) Rate of crystal growth is relatively large in the temperature range of 660°C to 720°C and attains to the maximum of 60μ/hr at 770°C.
    (4) The glass is devitrificated most rapidly and most uniformly under the condition of the particle size under 325 mesh and the heating temperature of 680°C, where the rate of nucleation exceeds the rate of nuclei growth.
    (5) Though the glass of this composition belongs to ones hard to be devitrificated, we have been able to obtain a polycrystalline product containing crystalline phase over 95% by heating after moulded for 2 hours at 450°C, at the rate of 0.1°C/min between 450°C and 550°C and 2.5°C/min between 550°C and 680°C and holding for 2 hours at 680°C, which consists of microcrystals of a few micron size and has the bending strength of 1000kg/cm2 to 1400kg/cm2.
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  • 1963 Volume 71 Issue 810 Pages 133a
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • 1963 Volume 71 Issue 810 Pages 133b
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • 1963 Volume 71 Issue 810 Pages A23-A28
    Published: 1963
    Released on J-STAGE: April 30, 2010
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  • [in Japanese]
    1963 Volume 71 Issue 810 Pages C273-C274
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • [in Japanese]
    1963 Volume 71 Issue 810 Pages C277-C282
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • [in Japanese]
    1963 Volume 71 Issue 810 Pages C283-C286
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • [in Japanese], [in Japanese]
    1963 Volume 71 Issue 810 Pages C287-C298
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • [in Japanese]
    1963 Volume 71 Issue 810 Pages C299-C303
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • [in Japanese]
    1963 Volume 71 Issue 810 Pages C305-C314
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • 1963 Volume 71 Issue 810 Pages C329-C332
    Published: 1963
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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